If you're a Steam user, you've probably noticed that Half-Life 2 is now available for pre-loading. Though the game has not yet gone gold, Valve is sending out certain parts of the game that will not change until the game ships. Of course, if you intend to buy the game in stores you don't need to pre-load the game through Steam. Valve sends over the following note which mentions Steam purchase options for the game will be announced soon
Half-Life 2 pre-loading begins to Steam account holders today. Over the coming days, those who have selected the pre-loading option will have encrypted Half-Life 2 files delivered to their PC. No purchase is required to pre-load HL2, but is required to activate the game. Purchase options will be released soon. Then, the moment the game is made available, those who have pre-loaded and purchased Half-Life 2 via Steam will be authenticated and ready to start playing. For more information, please visit www.steampowered.com